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How to Terraform a Dead Earth

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In the foreseeable future, a scientific community has discovered an alternate universe in which the solar system centers around a binary system of G-type suns, unlike the one G-type that ours orbits. The first planet is a diamond-crusted carbon planet twice as wide and eight times as massive as Earth, orbiting the second star from a distance of 1.1 million miles. The second planet is a Venus-like planet 175% as wide and five-and-a-half times as massive as Earth, orbiting both stars from a distance of 109 million miles. In the habitable zone is the third planet, an Earth-like planet 5800 miles wide with the following features:

  1. A gravity 75% that of Earth

  2. A retrograde rotation (suns rise from the west and set in the east) of 42 hours, a cycle that must be completed 827 times to make up one revolution (an "Asgardian" year)

  3. A single moon 3,474.2 miles wide and orbiting "Asgard" from a distance of 384,400 miles An axial tilt varying from 109.7 to 118.32 degrees every 1.4 million years

This alternate Earth is also more volcanically active, as indicated in the dimensions of its oceans:

  1. Shallow seas cover 40% of the oceans

  2. Deep seas cover 32% of the oceans

  3. Trenches and deeps cover 15% of the oceans

  4. Abyssal plains are the smallest feature of this alternate Earth's oceans, covering only 13%

The atmosphere consists primarily of carbon dioxide and methane, but it still has 2% as much oxygen as our Earth.

In every respect, it should have life. The problem with that is that it used to have life, but we have just missed a mass extinction severe enough to wipe the slate clean.

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This is a map of "Asgard". The red presented at the bottom of the map is the cause of the crisis that wiped out all life--a large basaltic plateau representing a volume of 80,000,000 cubic miles and a maximum elevation of 9,800 feet. Such a series of eruptions would have released enough greenhouse gases to wipe out even the toughest of organisms. So this Earth-like planet is too extreme for our first wave of terraforming pioneers, blue-green cyanobacteria, to thrive. Through a combination of natural and manmade means, how do we cool down the planet and possibly dilute the acidity of the oceans to the extent of making cyanobacterial colonization possible?

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7 comments

What makes you say cyanobacteria can't live there now? You've got liquid water on the surface, so there must be places with appropriate temperatures. And there must be rain, so fresh water somewhere, making the acidity of the oceans irrelevant. ‭Olin Lathrop‭ about 2 months ago

If an igneous province has a volume of 80 million cubic miles, then it would have released enough greenhouse gases to be too extreme for even extremophiles to thrive. That is what the Speculative Evolution Forum told me. ‭Enfield‭ about 2 months ago

@Enfield your question is way too specific. I'm not even sure what your question exactly is. Are you just saying "Suppose there was another earth, and it was devoid of life, how would we revive it?" If so, you should edit your question to have way less exposition. ‭Cazadorro‭ about 2 months ago

@Cazadorro Clarity is everything. If I remove any specifics, that would confuse everything and stray everyone from the question. ‭Enfield‭ about 2 months ago

Your planet has an orbital period of 34734 hours, or just about exactly four Earth years. In our solar system, Ceres (pretty close to smack in the middle of the asteroid belt) has an orbital period of 4.61 Earth years, so your planet should have an orbital circumference slightly less than that of Ceres. That would put it somewhere around 2-2.5 AU out, resulting in about a quarter of the insolation compared to 1 AU out. ‭aCVn‭ about 2 months ago

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Your question makes no sense due to its disregard of basic science.

The atmosphere consists primarily of carbon dioxide and methane

So did the early Earth's, and life was able to start here. This is clearly not a problem for some types of life.

Shallow seas cover 40% of the oceans

That's a great place for life. You've got generally warm water, sunlight, and minerals washing off the adjoining land masses.

Since you have liquid water on the surface, there are clearly places that aren't too hot or too cold for life, even just the life we know of here on Earth.

Deep seas cover 32% of the oceans

That together with your vulcanism is yet another habitat that we know life can survive in. Whole ecosystems have evolved on Earth around geothermal vents on the ocean floor.

Such a series of eruptions would have released enough greenhouse gases to wipe out even the toughest of organisms

This make no sense, and you give no justification for this conclusion. OK, so somehow a lot of CO2 was dumped into the atmosphere. That may have increased the temperature and CO2 content of the atmosphere. But, the end result still has liquid water on the surface, so it's not a runaway greenhouse situation like Venus. Some oganisms would have died out, but others would have been favored. Doing the same to Earth today might cause a mass extinction, but hardly a total extinction.

too extreme for our first wave of terraforming pioneers, blue-green cyanobacteria

Are you sure about that? And even if cyanobacteria as we have on Earth can't handle at least a few niches on this planet, they are certainly not the only choice for life, even oxygen-producing life.

The real problem you will have with building up oxygen if the planet never had much before, is that iron in the soil will bind with the oxygen for millions of years. Only after most available iron is oxidized, can you build up significant levels in the atmosphere. This is exactly what happened on the early Earth.

axial tilt varying from 109.7 to 118.32 degrees

How can an axial tilt exceed 90°? Think about it. After that, it's really just a 90°-N° tilt in the other direction with the poles flipped (which you already said is the case).

A single moon 3,474.2 miles wide and orbiting "Asgard" from a distance of 384,400 miles

So the moon is a bit larger and a bit farther than Earth's moon. How is the moon diameter relevant to 5 digits, though? This makes no sense. First, that level of precision is absurd for something that must have mountains and valleys. Second, I can't imagine what difference it would make if the moon was 3,474.0 or 3,475.0 miles wide instead.

orbiting both stars from a distance of 109 million miles

Huh? What? Even if you mean this to be the average distance to the two stars, that forces the stars to be implausibly close to each other.


Basically, you need to go back and re-think your world from a basis of science, unless you mean this to be a magic-driven place (in which case it's pointless asking what science tells us will happen).

8 comments

"How can an axial tilt exceed 90°?" Well, how else can we have western sunrises and eastern sunsets? "How is the moon diameter relevant to 5 digits, though?" Our moon measures 3,474.2 kilometers. But since this is Asgard, which is the direct reverse of Midgard ("Earth"), it's an opportunity to explore a similar switch in measurement. ‭Enfield‭ about 2 months ago

"Huh? What? Even if you mean this to be the average distance to the two stars, that forces the stars to be implausibly close to each other." That is the super Venus's distance to the two suns, not the alternate Earth's or the two suns'. ‭Enfield‭ about 2 months ago

@Enf: If any planet orbits two stars at 109 million miles, then the two stars must be absurdly close together. The distance between the stars must be a small fraction of this orbit radius, else a single orbit radius is meaningless. Let's say 10% to pick something. So the two stars are 11 million miles apart max? Again, go back to some basic science. ‭Olin Lathrop‭ about 2 months ago

Regarding the moon, the diameter is also largely irrelevant. The diameter and orbital radius (not even specified whether it's semi-minor or semi-major axis) plus the planet's radius allows deriving the angular size as viewed from the planet's surface, but that's about it. Mass and average density, along with orbital parameters (at least semi-minor and semi-major axis, or either plus orbital eccentricity), almost certainly matters a lot more to its interactions with the planet. ‭aCVn‭ about 2 months ago

@Enfield RE: ""How can an axial tilt exceed 90°?" once you get past 90° your reference changes. There is nothing making one side or the other the top. Imagine it cycles back and forth across the 90° point, is it the 'top' the 'top' you saw when you first looked, or is it the 'top' from the cycle before you looked? The magnetic poles of Earth flip locations, the same is likely on your planet, do you use the North of today or yesterday as the 'top'? ‭James Jenkins‭ about 2 months ago

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